1. Field of the Invention
The present invention relates to a substrate washing device for washing substrates such as semiconductor wafers while immersing them in process solutions.
2. Description of the Related Art
A washing system includes plural solution vessels and wafer transfer mechanisms and it serves to clean the surface of each of the wafers while immersing them in ammonia and fluorine acid solutions and pure water. Each of the wafer transfer mechanisms has wafer chucks and a wafer boat, which have their wafer holder sections each having a plurality of wafer holding grooves formed thereon.
The wafer holder sections must be erosion-resistant because they are immersed in various chemical (or process) solutions together with the wafers. The wafer holder section, particularly, of the wafer boat must be made of material excellent in erosion and heat resistances and high in strength because it is immersed in high temperature solution (or sulfuric acid solution higher than 100.degree. C., for example). It is therefore made of quartz.
When the wafers are transferred between the wafer chucks and the wafer boat, however, chipping is caused at those areas of the quartz-made wafer holder section which are contacted directly with the wafers. Particles are thus caused by this chipping and they adhere to the surface of each of the wafers. The efficiency of washing the wafers is thus lowered. Further, when the wafers collide with the wafer holder section while being carried, they themselves are damaged.